Dissertations / Theses: 'Climate in Africa'

1

Chin-Yee, Simon. "Defining climate policy in Africa : Kenya's climate change policy processes." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/defining-climate-policy-in-africa-kenyaas-climate-change-policy-processes(3b7440d0-7f08-4e87-b47d-ea4ad0a56d50).html.

Full text

Abstract:

This thesis seeks to investigate what shapes climate change policies in Kenya. Using Peter Haas' concept of usable knowledge, it argues the need to move beyond conventional perspectives on knowledge and power and provides a framework for understanding what knowledge and mechanisms are usable for policy makers. I argue that Kenyan climate policy is shaped by the interaction of knowledge and power across three crucial levels of influence - global, regional and national. As climate change forces us to rethink how we combine economic policies with environmental realities in Africa, each level encompasses distinct policy narratives where critical actors have an impact on national climate change policy. First, I argue that the standards, norms and regulations established by the global climate regime are directly reflected in national climate strategies of African countries, not only in terms of diplomatic moves to adhere to commitments made, but also in respect to benefiting from international mechanisms put in place to aid developing countries. Second, I examine the One Voice, One Africa narrative. This looks at the rise of the African Group of Negotiators within the global climate regime and their ability to influence Kenyan policy. Third, Kenya's climate change policy is shaped by the interaction of economic, political, and environmental constructs in national policy-making. The principle goal of this thesis is to open African environmental scholars and climate change policy analysts to a rigorous and flexible questioning of how climate policy processes operate in the African context.

APA, Harvard, Vancouver, ISO, and other styles

2

Mongie, Caitlin Claire. "Voluntary climate change disclosure in South Africa." Master's thesis, Faculty of Commerce, 2019. http://hdl.handle.net/11427/30897.

Full text

Abstract:

There is increasing evidence that anthropogenic carbon dioxide emissions are the major cause for global warming. A changing external environment and societal pressure is driving companies to respond to climate change and to limit further contribution where possible. Despite carbon emissions still being largely unregulated and carbon disclosure not being mandatory, many companies in South Africa have voluntarily decided to reduce emissions and make disclosures to the Carbon Disclosure Project (CDP). Institutional, socio-political and economic voluntary disclosure theories all indicate that there is a pressure for companies to monitor their climate mitigation, evaluate the costs of disclosing and manage stakeholders’ pressures by producing voluntary climate change disclosure. The CDP scores the disclosure made by each company as a measure of the company’s progress towards environmental stewardship. The highest CDP score indicates that a company has leadership in its efforts to environmental stewardship and so addressed stakeholders’ concerns. This study aims to determine which factors, either company specific or individual company responses within the CDP questionnaire, influence a high CDP climate change score for South African companies. The top 100 South African companies were selected using a full Johannesburg Stock Exchange (JSE) listing as at 31 March 2017 and the climate change programme score and individual company responses to the climate change questionnaire were obtained from the CDP for the five-year period from 2013 to 2017. A random effect model was used to examine the determinants of voluntary disclosure of carbon information. The results indicate that while CDP scores have improved post the signing of the Paris Agreement in December 2015, providing incentives for managing climate change has also led to improvements in the CDP score which results in improved climate change disclosure. Furthermore, the longer the company assesses climate change risks and opportunities into the future, the better its CDP score. This research contributes a more thorough understanding of disclosure theories, as established from these results. In terms of institutional theories, institutional investors should call for incentives to motivate for climate change management because companies might then be more likely to receive a better CDP score. In terms of socio-political theories, this study’s findings indicate that managers should be made aware that the further into the future they consider climate change risk management the better because this practice will result in the company obtaining an improved CDP score, while simultaneously managing stakeholders’ perceptions of the company. Additionally, this study contributes by making recommendations for companies and policy makers.

APA, Harvard, Vancouver, ISO, and other styles

3

Tirivarombo, Sithabile. "Climate variability and climate change in water resources management of the Zambezi River basin." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1002955.

Full text

Abstract:

Water is recognised as a key driver for social and economic development in the Zambezi basin. The basin is riparian to eight southern African countries and the transboundary nature of the basin’s water resources can be viewed as an agent of cooperation between the basin countries. It is possible, however, that the same water resource can lead to conflicts between water users. The southern African Water Vision for ‘equitable and sustainable utilisation of water for social, environmental justice and economic benefits for the present and future generations’ calls for an integrated and efficient management of water resources within the basin. Ensuring water and food security in the Zambezi basin is, however, faced with challenges due to high variability in climate and the available water resources. Water resources are under continuous threat from pollution, increased population growth, development and urbanisation as well as global climate change. These factors increase the demand for freshwater resources and have resulted in water being one of the major driving forces for development. The basin is also vulnerable due to lack of adequate financial resources and appropriate water resources infrastructure to enable viable, equitable and sustainable distribution of the water resources. This is in addition to the fact that the basin’s economic mainstay and social well-being are largely dependent on rainfed agriculture. There is also competition among the different water users and this has the potential to generate conflicts, which further hinder the development of water resources in the basin. This thesis has focused on the Zambezi River basin emphasising climate variability and climate change. It is now considered common knowledge that the global climate is changing and that many of the impacts will be felt through water resources. If these predictions are correct then the Zambezi basin is most likely to suffer under such impacts since its economic mainstay is largely determined by the availability of rainfall. It is the belief of this study that in order to ascertain the impacts of climate change, there should be a basis against which this change is evaluated. If we do not know the historical patterns of variability it may be difficult to predict changes in the future climate and in the hydrological resources and it will certainly be difficult to develop appropriate management strategies. Reliable quantitative estimates of water availability are a prerequisite for successful water resource plans. However, such initiatives have been hindered by paucity in data especially in a basin where gauging networks are inadequate and some of them have deteriorated. This is further compounded by shortages in resources, both human and financial, to ensure adequate monitoring. To address the data problems, this study largely relied on global data sets and the CRU TS2.1 rainfall grids were used for a large part of this study. The study starts by assessing the historical variability of rainfall and streamflow in the Zambezi basin and the results are used to inform the prediction of change in the future. Various methods of assessing historical trends were employed and regional drought indices were generated and evaluated against the historical rainfall trends. The study clearly demonstrates that the basin has a high degree of temporal and spatial variability in rainfall and streamflow at inter-annual and multi-decadal scales. The Standardised Precipitation Index, a rainfall based drought index, is used to assess historical drought events in the basin and it is shown that most of the droughts that have occurred were influenced by climatic and hydrological variability. It is concluded, through the evaluation of agricultural maize yields, that the basin’s food security is mostly constrained by the availability of rainfall. Comparing the viability of using a rainfall based index to a soil moisture based index as an agricultural drought indicator, this study concluded that a soil moisture based index is a better indicator since all of the water balance components are considered in the generation of the index. This index presents the actual amount of water available for the plant unlike purely rainfall based indices, that do not account for other components of the water budget that cause water losses. A number of challenges were, however, faced in assessing the variability and historical drought conditions, mainly due to the fact that most parts of the Zambezi basin are ungauged and available data are sparse, short and not continuous (with missing gaps). Hydrological modelling is frequently used to bridge the data gap and to facilitate the quantification of a basin’s hydrology for both gauged and ungauged catchments. The trend has been to use various methods of regionalisation to transfer information from gauged basins, or from basins with adequate physical basin data, to ungauged basins. All this is done to ensure that water resources are accounted for and that the future can be well planned. A number of approaches leading to the evaluation of the basin’s hydrological response to future climate change scenarios are taken. The Pitman rainfall-runoff model has enjoyed wide use as a water resources estimation tool in southern Africa. The model has been calibrated for the Zambezi basin but it should be acknowledged that any hydrological modelling process is characterised by many uncertainties arising from limitations in input data and inherent model structural uncertainty. The calibration process is thus carried out in a manner that embraces some of the uncertainties. Initial ranges of parameter values (maximum and minimum) that incorporate the possible parameter uncertainties are assigned in relation to physical basin properties. These parameter sets are used as input to the uncertainty version of the model to generate behavioural parameter space which is then further modified through manual calibration. The use of parameter ranges initially guided by the basin physical properties generates streamflows that adequately represent the historically observed amounts. This study concludes that the uncertainty framework and the Pitman model perform quite well in the Zambezi basin. Based on assumptions of an intensifying hydrological cycle, climate changes are frequently expected to result in negative impacts on water resources. However, it is important that basin scale assessments are undertaken so that appropriate future management strategies can be developed. To assess the likely changes in the Zambezi basin, the calibrated Pitman model was forced with downscaled and bias corrected GCM data. Three GCMs were used for this study, namely; ECHAM, GFDL and IPSL. The general observation made in this study is that the near future (2046-2065) conditions of the Zambezi basin are expected to remain within the ranges of historically observed variability. The differences between the predictions for the three GCMs are an indication of the uncertainties in the future and it has not been possible to make any firm conclusions about directions of change. It is therefore recommended that future water resources management strategies account for historical patterns of variability, but also for increased uncertainty. Any management strategies that are able to satisfactorily deal with the large variability that is evident from the historical data should be robust enough to account for the near future patterns of water availability predicted by this study. However, the uncertainties in these predictions suggest that improved monitoring systems are required to provide additional data against which future model outputs can be assessed.

APA, Harvard, Vancouver, ISO, and other styles

4

Olwoch, Jane Mukarugwiza. "Climate change and tick-host relationships in Africa." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-06082007-090301.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Bayor, Hypolite. "Diospyros in west Africa : morphology, molecules and climate." Thesis, University of Reading, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558778.

Full text

Abstract:

Diospyros is a pantropical genus occurring in the lower layers oftropical moist forests. As such the persistence of the forest may be critical to the survival of some species. Twenty-two species of Diospyros occur in the Upper Guinean biodiversity hotspot, seven of which are endemic. The effectiveness of vegetative characters used with computer-aided keys, DNA barcoding, phylogeny and species distribution modelling as tools to study the biodiversity of this area was investigated. A computer-aided multi-access key developed indicated that vegetative characters might be able to identify some species but more testing is required. The effectiveness of the proposed barcodes for plants (rbeL and matK) and psbA-trnH were tested. Bayesian trees showed that single regions produced unresolved trees but using the three regions combined could assign 26 accessions to species. Using TaxonDNA, matK and psbA-trnH were almost equally effective at 84.6% and 84.0% respectively in assigning field collected accessions to species however, rbeL identified only 37.4%. For a combined data set of Genbank and field data, proportion of accessions correctly assign to species was lower. TaxonDNA assigned 59.6%,49.3% and 75.1% accessions of rbeL, matK, and psbA-trnH respectively to species. Phylogenetic analysis using rbeL and matK shows that West African species may belong to at least four different lineages and these are scattered over the entire worldwide Diospyros phylogeny. Sister species mayor may not have overlapping ranges indicating that dispersal might contribute to speciation in Diospyros. The effect of climate change on five ofthe endemic species was investigated. Although reduction in predicted area for three species was observed, the area occupied by one was not affected while one species was predicted to have potential to expand its range which suggests genetic homogenization as a possible outcome. The availability and quality of data for species distribution modelling offive species was also investigated. Data were insufficient for two species not modelled and gaps in sampling were also evident. The effect of biased geographic sampling was to inflate AUC values of distribution models. Overall, it is clear that technologies such as computer-aided keys, DNA barcoding, phylogenetic analysis and climate envelope modelling help to study and understand diversity in this Western African biodiversity hotspot. The identification tools can be challenging to develop but will allow better surveys and in turn help to fill the data gaps revealed in the climate envelope modelling studies.

APA, Harvard, Vancouver, ISO, and other styles

6

Egbebiyi, Temitope Samuel. "Future changes in extreme rainfall events and African easterly waves over West Africa." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20581.

Full text

Abstract:

This study examines the relationship between African Easterly Waves (AEWs) and extreme rainfall events over West Africa, and investigates how climate change could alter this relationship in the future. Satellite observations, reanalysis data, and regional climate model (RCA4) simulations (forced with eight global climate simulations) were analysed for the study. The study used the 95th percentile of daily rainfall as a threshold to identify extreme rainfall events, and applied spectral analysis to extract 3-5 days and 6-9 days AEWs from 700hPa meridional wind component over West Africa. The capability of RCA4 to reproduce the rainfall climatology, extreme rainfall events, the characteristics of AEWs and the contribution of AEWs to extreme rainfall events over the region during the past climate (1971-2005) was examined and quantified using statistical analysis. The future changes (2031-2065) in these parameters were projected for the RCP4.5 and RCP8.5 climate-change scenarios. The results of the study show that RCA4 gives a realistic simulation of the West African climate, including the annual rainfall pattern, the structure of AEWs, and the characteristics of the African Easterly Jet that feeds AEWs. The bias in the simulated threshold of extreme rainfall is within the uncertainty of the observed values. The model also captures the link between the structure of AEWs and the rainfall pattern over West Africa, and shows that the percentage contribution of AEWs to extreme rainfall events over the region ranges from 20 to 60%, as depicted by reanalysis data. For the RCP4.5 and RCP8.5 scenarios, the RCA4 ensemble mean projects a future increase in annual rainfall and in the frequency and intensity of extreme rainfall events over the sub-continent, but the increase is generally higher for the RCP8.5 scenario. It also projects a decrease in the frequency of rain days, no changes in the structure of the AEWs, and an increase in the variance of the waves. However, the simulations from the ensemble mean shows no substantial changes in the contribution of AEWs to the extreme rainfall events, suggesting that the increase in the frequency and intensity of the extreme rainfall events may not be attributable to the changes in AEWs. The study's application is in understanding and mitigating the future impact of climate extremes over West Africa.

APA, Harvard, Vancouver, ISO, and other styles

7

Foto, Tongai. "A measure of the investment climate in South Africa." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8987_1297754095.

Full text

Abstract:

Investor confidence is a concept many investors are constantly trying to gauge. In practice however these concepts are usually not easy to measure. This study attempts to capture the total sum of investor perception in South Africa by examining market behaviour. Data from the JSE/FTSE (1995-2009) will be used to determine an Equity Risk Premium. Bond Yield Spreads will also be calculated from data provided by I-NET BRIDGE. An amalgamation of these components will produce the proposed Investment Confidence Index. Similar indices currently on the South African Market are based on subjective surveys and might therefore be biased. The proposed index which is a first in SA will prove invaluable to practitioners in the financial sector.

APA, Harvard, Vancouver, ISO, and other styles

8

Veljanoska, Stefanija. "Agricultural risk, remittances and climate change in rural Africa." Thesis, Paris 1, 2016. http://www.theses.fr/2016PA01E057/document.

Full text

Abstract:

Dans le cadre de cette thèse, nous nous intéressons à l'étude des décisions des ménages ruraux Ougandais en termes de gestion des risques climatiques. Dans un premier temps, nous testons l'impact des transferts des fonds des migrants sur le niveau de spécialisation des cultures agricoles ainsi que le niveau de risque du portefeuille des cultures des ménages contraints par l'accès aux marchés du crédit et de l'assurance. Nous complétons cette première analyse avec une étude sur la capacité des transferts des migrants à encourager les ménages à utiliser des inputs plus risqués tels que les engrais. Dans un troisième temps, nous explorons si le morcellement des terres peut réduire les effets négatifs de la variabilité des précipitations sur les rendements des cultures agricoles. Le dernier objectif de cette thèse est d'analyser l'impact de l'inégalité d'accès à l'eau sur l'intensité et l'incidence des manifestations et des émeutes au sein d'un pays. Le point central et commun aux différents chapitres est la variabilité climatique : quelles sont les conséquences pour les ménages agricoles ; comment les ménages peuvent se protéger contre les aléas climatiques et quelles sont les implications pour la disponibilité de l'eau et les conflits. Telles sont les questions que la thèse vise à aborder à travers une approche micro-économétrique
The dissertation provides evidence on the agricultural decisions of rural Ugandan households in terms of risk management against weather variability. First, I study the impact of remittances sent by migrants on households' degree of crop specialization and crop riskiness, as remittances may, to some extent, relieve credit and risk constraints. I complete the first objective with a second analysis that explores if remittances can motivate households to use riskier inputs - fertilizers. Third, I examine whether land fragmentation can reduce the negative impacts of rainfall variability on farmers' crop yields. In the final chapter, I test whether inequality in access to water for consumption may increase the incidence and the intensity of low-level conflicts. The central and common theme of the different chapters is weather variability: what are the consequences for agricultural households, how can households protect themselves against weather fluctuations and what are the implications for water availability and social conflict. Those are the questions that the dissertation aims at addressing with a micro-level empirical approach

APA, Harvard, Vancouver, ISO, and other styles

9

Abdussalam, Auwal Farouk. "Climate influences on infectious diseases in Nigeria, West Africa." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5368/.

Full text

Abstract:

Meningitis and cholera have remained major health burden in Nigeria, especially in the heavily populated northwest region – which is identified as one of the “hotspots” of climate change. The strong sensitivity that both diseases exhibit to climate is raising concern that future anthropogenic climate change may exacerbate the occurrence of the diseases. This thesis aimed at modelling the influences of climate on the incidence of the selected diseases, and assessing their future risk in northwest Nigeria. The aim is achieved by first, investigating and understanding the spatial and time characteristics of both meteorological and diseases conditions in the region. This was followed by developing and validating suites of empirical statistical models capable of explaining and predicting both diseases. Models that are specifically designed for climate change studies were applied to estimate the future impact of climate change, by forcing them with simulations from an ensemble of statistically downscaled Atmosphere-ocean Global Climate Models (AOGCMs), for three different scenarios in the early and late 21st century. Results from developed models indicate the significant roles of both meteorological and socioeconomic factors on incidence of diseases. Evaluation of models developed with 1-month lagged explanatory variables suggest the potential to predict both diseases cases up to a month to aid decision making. Projection results suggest that future temperature increases due to climate change has the potential to significantly increase diseases cases in all scenarios and time slices. It is noteworthy that the projections result represents only the climatological potential for increased cases due to climate change, assuming that the present prevention strategies remain similar in the future.

APA, Harvard, Vancouver, ISO, and other styles

10

Pinto, Izidine S. de Sousa. "Future changes in extreme rainfall events and circulation patterns over southern Africa." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16781.

Full text

Abstract:

Includes bibliographical references
Changes in precipitation extremes are projected by many global climate models as a response to greenhouse gas increases, and such changes will have significant environmental and social impacts. These impacts are a function of exposure and vulnerability. Hence there is critical need to understand the nature of weather and climate extremes. Results from an ensemble of regional climate models from the Coordinated Regional Downscaling Experiment (CORDEX) project are used to investigate projected changes in extreme precipitation characteristics over southern Africa for the middle (2036-2065) and late century (2069-2098) under the representative concentration pathway 4.5 (RCP4.5) and 8.5 (RCP8.5). Two approaches are followed to identify and analyze extreme precipitation events. First, indices for extreme events, which capture moderate extreme events, are calculated on the basis of model data and are compared with indices from two observational gridded datasets at annual basis. The second approach is based on extreme value theory. Here, the Generalized Extreme Value distribution (GEV) is fitted to annual maxima precipitation by a L-moments method. The 20-year return values are analyzed for present and future climate conditions. The physical drivers of the projected change are evaluated by examining the models ability to simulate circulation patterns over the regions with the aid of Self-Organizing Maps (SOM).

APA, Harvard, Vancouver, ISO, and other styles

11

Lawal, Kamoru Abiodun. "Understanding the variability and predictability of seasonal climates over West and Southern Africa using climate models." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16556.

Full text

Abstract:

Includes bibliographical references
A good understanding of seasonal climate and the limit to which it can be predicted is crucial in addressing various socio-economic challenges in Africa. However, how to improve the capability of the dynamical models of the climate system in reproducing the regional seasonal climate variability and in replicating the role of various atmospheric circulation anomalies on the regional variability remains a major challenge. Thus far, understanding of seasonal climate over these regions, as well as the ability of climate models to predict them, has focused on the agreement of simulations of dynamical models of the climate system, rather than considering outliers as potentially vital contributors to understanding and predictability. This thesis uses discrepancy in a large ensemble of climate simulations as a tool to investigate variability in dominant seasonal rainfall and temperature patterns (i.e. classes) over West and Southern Africa, to examine the capability of climate models in reproducing the variability, and to study the predictability of the seasonal climates over South Africa. The dominant classes of variability (of rainfall and maximum temperature fields) in both regions are examined based on the Self-Organizing Map (SOM) classifications. The sequences in which each class occurs cannot be linked simply to a single common index of global scale atmospheric circulation anomalies, implying that the chaotic regional atmospheric circulations that modulate the global scale modes of variability are indispensable. The climate model examined adequately reproduces the dominant classes of seasonal climate over West and Southern Africa.

APA, Harvard, Vancouver, ISO, and other styles

12

O'Brien, Eileen M. "Climate and woody plant species richness : analyses based upon southern Africa's native flora with extrapolations to subsaharan Africa." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670313.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Waha, Katharina. "Climate change impacts on agricultural vegetation in sub-Saharan Africa." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6471/.

Full text

Abstract:

Agriculture is one of the most important human activities providing food and more agricultural goods for seven billion people around the world and is of special importance in sub-Saharan Africa. The majority of people depends on the agricultural sector for their livelihoods and will suffer from negative climate change impacts on agriculture until the middle and end of the 21st century, even more if weak governments, economic crises or violent conflicts endanger the countries’ food security. The impact of temperature increases and changing precipitation patterns on agricultural vegetation motivated this thesis in the first place. Analyzing the potentials of reducing negative climate change impacts by adapting crop management to changing climate is a second objective of the thesis. As a precondition for simulating climate change impacts on agricultural crops with a global crop model first the timing of sowing in the tropics was improved and validated as this is an important factor determining the length and timing of the crops´ development phases, the occurrence of water stress and final crop yield. Crop yields are projected to decline in most regions which is evident from the results of this thesis, but the uncertainties that exist in climate projections and in the efficiency of adaptation options because of political, economical or institutional obstacles have to be considered. The effect of temperature increases and changing precipitation patterns on crop yields can be analyzed separately and varies in space across the continent. Southern Africa is clearly the region most susceptible to climate change, especially to precipitation changes. The Sahel north of 13° N and parts of Eastern Africa with short growing seasons below 120 days and limited wet season precipitation of less than 500 mm are also vulnerable to precipitation changes while in most other part of East and Central Africa, in contrast, the effect of temperature increase on crops overbalances the precipitation effect and is most pronounced in a band stretching from Angola to Ethiopia in the 2060s. The results of this thesis confirm the findings from previous studies on the magnitude of climate change impact on crops in sub-Saharan Africa but beyond that helps to understand the drivers of these changes and the potential of certain management strategies for adaptation in more detail. Crop yield changes depend on the initial growing conditions, on the magnitude of climate change, and on the crop, cropping system and adaptive capacity of African farmers which is only now evident from this comprehensive study for sub-Saharan Africa. Furthermore this study improves the representation of tropical cropping systems in a global crop model and considers the major food crops cultivated in sub-Saharan Africa and climate change impacts throughout the continent.
Landwirtschaft ist eine der wichtigsten menschlichen Aktivitäten, sie stellt Nahrungsmittel und andere landwirtschaftliche Produkte für weltweit 7 Milliarden Menschen zur Verfügung und ist in den Ländern Afrikas südlich der Sahara von besonderer Bedeutung. Die Mehrheit der afrikanischen Bevölkerung bestreitet ihren Lebensunterhalt in der Landwirtschaft und wird von Klimaänderungen stark betroffen sein. Die Doktorarbeit ist durch die Frage motiviert, wie sich von Klimamodellen vorhergesagte Temperaturerhöhungen und sich verändernde Niederschlagsverteilungen auf die landwirtschaftliche Vegetation auswirken werden. Die Forschungsfragen in diesem Kontext beschäftigen sich mit regionalen Unterschieden von Klimaänderungen und ihren Auswirkungen auf die Landwirtschaft und mit möglichen Anpassungsstrategien die mit geringem technischem Aufwand genutzt werden können. In diesem Zusammenhang wird schnell deutlich, dass Daten über die komplexen landwirtschaftlichen Systeme in Afrika südlich der Sahara häufig nur selten vorhanden sind, aus fragwürdigen Quellen stammen oder von schlechter Qualität sind. Die Methoden und Modelle zur Untersuchung der Auswirkungen von Klimaänderungen auf die Landwirtschaft werden zudem ausschließlich in Europa oder Nordamerika entwickelt and häufig in den temperierten Breiten aber seltener in tropischen Gebieten angewendet. Vor allem werden globale, dynamische Vegetationsmodelle in Kombination mit Klimamodellen eingesetzt um Änderungen in der landwirtschaftlichen Produktion auf Grund von Klimaänderungen in der zweiten Hälfte des 21.Jahrhunderts abzuschätzen. Die Ergebnisse der Arbeit zeigen einen mittleren Ertragsrückgang für die wichtigsten landwirtschaftlichen Pflanzen um 6% bis 24% bis 2090 je nach Region, Klimamodell und Anpassungsstrategie. Dieses Ergebnis macht deutlich, dass Landwirte die negativen Folgen von Klimaänderungen abschwächen können, wenn sie die Wahl der Feldfrucht, die Wahl des Anbausystems und den Aussaattermin an geänderte Klimabedingungen anpassen. Die Arbeit stellt methodische Ansätze zur Berechung des Aussaattermins in temperierten und tropischen Gebieten (Kapitel 2) sowie zur Simulation von Mehrfachanbausystemen in den Tropen vor (Kapitel 3). Dabei werden wichtige Parameter für das globale, dynamische Vegetationsmodell LPJmL überprüft und neu berechnet. Es zeigt sich, dass das südliche Afrika und die Sahelregion die am stärksten betroffenen Regionen sind, vor allem aufgrund von Niederschlagsänderungen, weniger aufgrund von Temperaturerhöhungen. In den meisten anderen Teilen, vor allem Zentral- und Ostafrikas bedingen Temperaturerhöhungen Rückgänge der Erträge (Kapitel 4). Diese Arbeit leistet einen wichtigen und umfassenden Beitrag zum Verständnis der Auswirkung von Klimaänderung auf die landwirtschaftliche Vegetation und damit zu einem großen Teil auf die Lebensgrundlage von afrikanischen Landwirten.

APA, Harvard, Vancouver, ISO, and other styles

14

Vincent, Katharine. "Gendered vulnerability to climate change in Limpopo province, South Africa." Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439905.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Chapa, Srinivasa Rao. "Climate studies over sub-Saharan Africa using cold cloud duration." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385214.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Shannon, Debbie Anne. "Land surface response to climate change forcing over Southern Africa." Doctoral thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5286.

Full text

Abstract:

The land surface is important to the climate system for the exchanges of moisture, momentum and heat. Momentum, radiation, and sensible and latent heat fluxes between the atmosphere and the surface will likely affect atmospheric dynamics, temperature, precipitation and humidity fields (Sato et ai., 1989). These may subsequently feed back into the land surface processes as part of a cyclical system. Therefore it is evident that our livelihood is largely dependent on interactions and exchanges between the land surface and climate system (Henderson-Sellers et ai., 1993) and it is thus essential that we gain a better understanding of the interactive sensitivity. This is of particular relevance in the context of the portended future global climate change. In the present study the interactions between the land surface and the atmosphere are considered over the southern African region. This region has a climate showing a high degree of spatial and temporal variability, most notably with rainfall. Regional climates are characterised by summer, winter and all-year-round rainfall. There are steep vegetation gradients and a wide range of vegetation types adapted to suit the variable climate. These factors, combined with the societal implications of changes in the climate and land surface systems, make southern Africa a challenging and important study domain for examining the sensitivity between the different elements of the atmosphere and biosphere. This research makes use of a biosphere model driven by climate change data derived from a general circulation model (GCM). Regions susceptible and sensitive to changes on an annual and seasonal basis are identified and examined. The thesis comprises 8 chapters. The first chapter, Chapter 1, provides some background information on climate change, biosphereatmosphere interactions, GCMs and transient simulations, vegetation models and vegetation representation over southern Africa. This chapter also sets out the research objectives. The following chapter, Chapter 2, introduces the atmospheric GCM model data from the Hadley Centre Model (HadCM2) used in the analysis. The chapter additionally provides a detailed description of the biosphere model, the Integrated Biosphere Simulator (IBIS). Chapter 3 examines the Hadley Centre HadCM2 GCM input data used in driving the biosphere model, while Chapter 4 presents the input forcing data and configuration of the IBIS model. In Chapter 5 the results of the IBIS model simulation are examined on the annual scale and in Chapter 6 the results are examined on the seasonal scale. Some of the implications of climate change are considered in Chapter 7. This chapter also places the HadCM2 GCM model data used in driving IBIS into the context of the latest emissions scenarios. In the final chapter, Chapter 8, an overview summary is provided and conclusions are drawn.

APA, Harvard, Vancouver, ISO, and other styles

17

Quagraine, Kwesi Akumenyi. "Dynamics of co-behaviour of climate processes over Southern Africa." Doctoral thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33916.

Full text

Abstract:

Large-scale climate processes such as El Niño-Southern Oscillation (ENSO), Antarctic Oscillation (AAO), and many others, play varying roles in regional climate variability across the world. While the role of singular processes have been explored in many studies, the combined influence of multiple large-scale processes has received far less attention. Key to this is the challenge of developing methodologies to support the analysis of multiple processes interacting in potentially non-linear ways (co-behaviour) in a particular region. This study details the development of such a methodology and demonstrates its utility in the analysis of the co-behaviour of largescale process interactions on regional precipitation and temperature variability over southern Africa. The study defines co-behaviour as the interaction of large-scale processes that may influence regional circulation leading to climate variability. A novel methodology which involves a combination of analysis techniques such as Self-Organizing Maps (SOM) and Principal Component Analysis (PCA) is developed to identify and quantify such co-behaviour which accommodates potentially non-linear interactions. This methodology is evaluated in the context of southern African regional climate using three key processes, namely ENSO, AAO and Inter-tropical Convergence Zone (ITCZ), and characterizations of regional circulation, and temperature and rainfall variability. Analysis of co-behaviour under observed conditions identifies results that concur with prior studies, in particular the dominant regional response to ENSO, but also establishes key examples of co-behaviour such as the role of the AAO in moderating and altering the regional response to ENSO which is important for understanding regional climate variability. Application of the approach to Global Climate Model (GCM) simulations of past climate reveals that while many GCMs are able to capture individual processes, in particular ENSO, they fail to adequately represent regional circulation variability and key observed co-behaviour. The study therefore clearly demonstrates the importance of co-behaviour in understanding regional climate variability as well as showing the usefulness of the new methodology in investigating co-behaviour. Finally, the new insights into evaluating model performance through the lens of core climate processes and their interaction provides a significant step forward in both model development and application for decision making.

APA, Harvard, Vancouver, ISO, and other styles

18

Nhemachena, Charles. "Agriculture and future climate dynamics in Africa impacts and adaptation options /." Thesis, Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-05302009-122839/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Osima, Sarah Emerald. "Understanding a high resolution regional climate model's ability in simulating tropical East Africa climate variability and change." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16716.

Full text

Abstract:

Includes bibliographical references
The main aim of this thesis is to investigate the potential benefits of increasing resolution in regional climate models in the simulation of climate variability and change over East Africa. This study is based on two high resolution regional climate simulations with a horizontal resolution of 50km and 10km, respectively. These represent present day climate and a projection of future climate change over East Africa. The regional climate model (RCM) used here is HIRHAM5, which is driven by the global circulation model (ECHAM5). Downscaled ECHAM5 output is used to drive the 50km HIRHAM5 simulation for the period 1950-2100, and output from this simulation is used to drive the 10km simulation for three time slices: 1980-1999, representative for present-day climate and two time slices for near future (2046-2065) and far future (2080- 2099), respectively. HIRHAM5 is evaluated with respect to the observed mean climatologies of rainfall, surface temperature and surface winds over East Africa, and representations of the observed annual cycles and inter-annual variability of rainfall and surface temperature. This study utilizes reanalysis and observational datasets: a hindcast of HIRHAM5 forced with ERA Interim, as well as two observation datasets for temperature and rainfall. Since reanalyses aim to make "best use" of all available observations by making a physically consistent representation continuous in time and space, and since there is a paucity of observations over many parts of Africa, the ERAI reanalysis is also used as a best estimate for model evaluation. Additionally, for evaluation of the bimodal nature of East Africa's rainfall, especially over Tanzania, three stations run by the Tanzania Meteorological Agency were used. The model data used in th is evaluation ranges from 1980 to 2006 iv HIRHAM5 demonstrates reasonable skill in the reproduction of observed patterns of mean climatology of rainfall, surface temperature and winds over East Africa. Moreover, the patterns of annual cycles of rainfall and surface temperature in the bimodal nature of East Africa are well represented. Furthermore, the model showed reasonable skill in the representation of the inter- annual variability and ENSO signals as suggested by the observation. Despite these strengths, HIRHAM5 shows some shortcomings. One weakness of the model is the simulation of the magnitude of a given variable over a specific region. For example, HIRHAM5 driven by ERAI underestimates rainfall and overestimates surface temperature over the entire domain of East Africa. The higher resolution HIRHAM5 (10km resolution) overestimates rainfall over high ground. The model bias could be due in part to the inadequacy of the observation networks in East Africa, represented in this thesis by the CRU and FEWS datasets. However, these two datasets draw on some different sources and neither do they have the same resolution. FEWS is a high resolution data (0.1 o ) gridded satellite-derived precipitation estimate covering the entire African continent while CRU datasets is a relatively low resolution (0.5 o ) dataset based on rain gauge monthly precipitation only; in addition , near surface temperature is also available. As no reliable wind observations exist, wind data was taken from the ERA-Interim reanalysis. The different observational datasets do not agree particularly well, which impedes evaluating the quality of the HIRHAM5 simulations, in particular the high resolution one. So while the higher resolution HIRHAM5 appears to be generally reliable, caution must be exercised in formulating conclusions from the results, especially over high ground and remote areas without adequate observation data. Under these constraints, the results suggest HIRHAM5 may be useful for assessing climate variability and change over East Africa. A weakness of the analysis presented here is that only one combination of GCM and RCM could be investigated in depth due to computer and time constraints. Therefore the results presented here, if used in application for climate change adaptation, should be considered in conjunction with a broader suite of data, such from the CORDEX programme. This has potential to increase the reliability of information about climate variability and change at a regional to local level necessary for impact assessment.

APA, Harvard, Vancouver, ISO, and other styles

20

Tabalaza, Nomthetho. "The impact climate change on rural households in Binfield village." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/20626.

Full text

Abstract:

Climate change poses a major environmental challenge, due to its adverse effects on human settlement patterns and food security. The global phenomenon upsets seasonal shifts, leading to changes in planting dates and weather patterns. This unpredictability has severe and adverse effects on farmers and rural communities, as variable environmental factors govern activities related to daily sustenance and food availability. The kind of rapid and intense climate change that South African rural spaces are experiencing now, increase the likelihood of extreme weather events such as droughts, heat waves and floods. There are growing concerns that the rural poor will be unable to adapt. Rural livelihoods are therefore facing overwhelming and extensive environmental threats, while rural dwellers are finding it difficult to adapt and cope. As a result, climate change can thus be described as one of the most complex and dangerous environmental problems challenging rural livelihoods today. The aim of this study was to explore the impact of climate change on rural poverty at Binfield village in the Eastern Cape and to identify the livelihood activities practiced. Furthermore, the research was conducted to ascertain how rural livelihood activities are affected by climate change and identify and assess the effectiveness of adaption strategies employed by the households. The research also aimed to explore and establish further adaptation strategies. This study made use of a qualitative research method. Babooa (2008) argues that qualitative research is concerned with stories and accounts including subjective understandings, feelings, opinions and beliefs. The study used both primary and secondary data for data. The researcher adopted interviews and field observation for primary data whilst secondary data was sourced from journals, articles and internet sources. O‘ Leary (2004) describes the interview as a method of collecting data where the interviewer asks the Interviewee open-ended questions. The questions were based on the key areas of interest. Qualitative research methods are aimed at understanding the rich, complex characteristic nature of human phenomena. Qualitative methods are concerned with understanding human behaviour from the participant‘s own frame of reference.

APA, Harvard, Vancouver, ISO, and other styles

21

Heyligers-van, Zyl Ilonka. "The relationship between collective climate, organisational commitment and intention to stay." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53670.

Full text

Abstract:

Thesis (Mcomm)--University of Stellenbosch, 2003.
ENGLISH ABSTRACT: A need was identified for a proactive strategy for reducing voluntary turnover levels within the mining industry. From the onset it was established that a multi-dimensional approach would be the most appropriate. Organisational commitment and organizational climate were identified as variables that were likely to influence intentions to stay. Moreover, it was hypothesised that organisational climate would directly influence organisational commitment levels. Both organisational climate and organisational commitment have been subjected to considerable controversy with respect to conceptual and methodological issues. This has resulted in the diverse array of approaches currently found in the literature and has threatened the usefulness of both constructs. An overview of existing literature indicated that little is known regarding the relationship between organisational climate, organisational commitment and intention to stay within the specific industry. The current study therefore investigated the existing relationship between collective climate, organisational climate and intent to stay within the mining industry. Research objectives were achieved by means of hierarchical cluster analysis, canonical correlational analysis and standard multiple regressions. All measures were subjected to confirmatory factor analysis. The results indicated that multiple collective climates existed in the various departments. A positive relationship was found between collective climate and organisational commitment, as well as between collective climate and intent to stay.
AFRIKAANSE OPSOMMING: 'n Behoefte aan proaktiewe intervensies, gemik op die vermindering van vrywillige arbeidsomset, is in 'n organisasie in die mynindustrie geïdentifiseer. Dit was vanuit die staanspoor ooglopend dat 'n multidimensionele benadering toepaslik sou wees. Organisasieklimaat en organisasie-verbondenheid is as moontlike veranderlikes geïdentifiseer wat 'n invloed op omsetbedoelings mag uitoefen. 'n Verdere hipotese had betrekking op die verband tussen organisasieverbondenheid en omset-bedoelings. Beide konstrukte het reeds aansienlike kontroversie met betrekking tot konseptueIe en metodologiese aspekte ontlok. Laasgenoemde het onder meer gelei tot die opkoms van 'n aantal uiteenlopende konseptueIe benaderings tot hierdie konstrukte, met die gevolg dat die empiriese bydraes wat hul tot die veld van Organisasiesielkunde maak, toenemend bevraagteken is. 'n Literatuuroorsig het aangedui dat 'n leemte met betrekking tot die onderwerp binne die bepaalde industrie bestaan. Weinig empiriese steun is egter gevind ten opsigte van 'n verband tussen organisasieklimaat, organisasie-verbondenheid en omset-bedoelings. Die betrokke studie het dus ten doel gehad die ondersoek van 'n verband tussen groepklimaat, organisasieverbondenheid en omsetbedoelings. Ten einde bogenoemde verbande te ondersoek, is gebruik gemaak van hiërargiese tros-analise, kanoniese korrelasionele analise, asook standaardmeervoudige regressie-ontledings. Die navorsingsbevindinge het bevestig dat 'n beduidende en positiewe verband tussen groepklimaat en organisasieverbondenheid bestaan. Daar is verder aangetoon dat omset-bedoelinge beduidend met groepklimaat, sowel as organisasieverbondenheid korreleer. 'n Sterker verband is tussen organisasieverbondenheid en omset-bedoelinge gevind.

APA, Harvard, Vancouver, ISO, and other styles

22

Anyanwu, Raymond Ndubisi. "An assessment of climate change science literacy and climate change pedagogical literacy of geography teachers in the Western Cape." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96831.

Full text

Abstract:

Thesis (PhD)--Stellenbosch University 2015.
ENGLISH ABSTRACT: This survey research employed a criterion-referenced multiple-choice questionnaire to collect data from 194 FET Geography teachers in the Western Cape province to assess their level of literacy in both climate change science and climate change pedagogy, and to determine the influence of gender, age, qualification, specialisation, experience, grade mostly taught, their experience in providing instruction on climate change and the location of their school. Aspects of climate change science assessed include: climate processes and probable causes of climate change; climate change impacts; and climate change responses. Aspects of climate change pedagogy assessed include: the aims and significance of climate change education; and constructivist teaching principles and practice. The collected data was analysed using percentage frequencies to determine the teachers‟ level of literacy in climate change science and climate change pedagogy; the Mann-Whitney and Kruskal-Wallis tests were used to determine the influence of the mediating variables on climate change science literacy and climate change pedagogical literacy, respectively. The results indicate that Geography teachers in the Western Cape Province demonstrated „High‟ literacy in climate change science and „Low‟ literacy in climate change pedagogy. Factors such as school location, gender, age and teaching experience were found to have a significant influence on climate change science literacy; whereas qualification, specialisation, grade mostly taught and experience in providing instruction on climate change did not. Conversely, teaching experience and grade mostly taught had a significant influence on climate change pedagogical literacy; whereas school location, gender, age, qualification, specialisation and experience in providing instruction on climate change did not. Based on these findings, it is recommended that professional development interventions in climate change pedagogy are required in order to expose Geography teachers to the aims and significance of climate change education and methods of facilitating problem-based, learner-centred instruction on climate change.
AFRIKAANSE OPSOMMING: Hierdie opnamenavorsing het gebruik gemaak van ‟n kriteriumverwysing- meerkeusige vraelys om data by 194 VOO Aardrykskunde onderwysers in die Wes-Kaap provinsie te versamel om hulle vlak van geletterdheid in beide die wetenskap en pedagogie van klimaatsverandering te bepaal en om die invloed van geslag, ouderdom, kwalifikasie, spesialisasie, ervaring, graad wat die meeste onderrig is, hulle ervaring van onderrig oor klimaatsverandering en die ligging van hulle skool te bepaal. Aspekte van klimaatsverandering wat geassesseer is, het klimaatsprosesse en moontlike oorsake van klimaatsverandering, impakte van klimaatsverandering en reaksies op klimaatsverandering ingesluit. Aspekte van die pedagogie van klimaatsverandering wat geassesseer is, het die doelwitte en betekenisvolheid van opvoeding oor klimaatsverandering en konstruktivistiese onderrigbeginsels en -praktyk ingesluit. Die versamelde data is met persentasiefrekwensie geanaliseer om die onderwysers se vlak van geletterdheid in die wetenskap en pedagogie van klimaatsverandering te bepaal; die Mann-Whitney en Kruskal-Wallis toetse is gebruik om die invloed van bemiddelende veranderlikes op geletterdheid met betrekking tot die wetenskap en pedagogie van klimaatsverandering onderskeidelik te bepaal. Die resultate dui aan dat Aardrykskunde-onderwysers in die Wes-Kaap „Hoë‟ geletterdheid in die wetenskap van klimaatsverandering en „Lae‟ geletterdheid in die pedagogie van klimaatsverandering getoon het. Faktore soos ligging van die skool, geslag, ouderdom en onderrigervaring het ‟n betekenisvolle invloed op geletterdheid in klimaatsverandering gehad, terwyl kwalifikasie, spesialisasie, graad wat die meeste onderrig is en ervaring van onderrig oor klimaatsverandering nie so ‟n invloed gehad het nie. In teenstelling het onderrigervaring en graad wat die meeste onderrig is, ‟n betekenisvolle invloed op geletterdheid in klimaatsverandering gehad, terwyl ligging van die skool, geslag, ouderdom, kwalifikasie, spesialisasie en ervaring van onderrig oor klimaatsverandering nie so ‟n invloed gehad het nie. Op grond van hierdie resultate kan gesê word dat professionele ontwikkelingsingrypings in die pedagogie van klimaatsverandering nodig is om Aardrykskunde-onderwysers bloot te stel aan die doelwitte en belangrikheid van onderwys oor klimaatsverandering en metodes om probleemgebaseerde, leerdergesentreerde onderrig oor klimaatsverandering te fasiliteer.

APA, Harvard, Vancouver, ISO, and other styles

23

Kgatuke, Mary-Jane Morongwa. "Internal variability of the regional climate model RegCM3 over Southern Africa." Diss., Pretoria [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08132007-091356.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Rabie, Elsa. "The impact of climate change on human security in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2214.

Full text

Abstract:

Thesis (MA (Political Science))--Stellenbosch University, 2008.
The Stern Review on the Economics of Climate Change is conclusive that climate change will lead to scarcity of the basic resources that sustain life for people around the world – fresh water supplies, food production and land for habitation and cultivation. It is argued that environmental scarcity leads to migration which in turn results in conflict in the receiving area as competition over resources develops. Based on the main theories relating to resource scarcity and conflict, the purpose of this study is to examine the link between climate change and human security. The relevance of this research is the fact that the Stern Review concludes that climate change poses a serious threat to the world and that Africa will be one of the hardest hit continents. Africa is already vulnerable to climate variability and has the least capacity to respond, and this study aims to establish the impacts of resource scarcity on human security in South Africa. The theoretical approach addresses the much debated concept of ‘human security’ as it has developed since the end of the Cold War and the analysis is based on the main conflict theories that maintain that competition over access to scarce resources is one of the root causes of violent conflict. The research design for this study is of an empirical nature with the units of analysis being states, physical events and processes and the resulting human actions. It is a descriptive analysis, interpreting the impact of climate change on scarce resources and the resulting propensity for conflict. Much of the violence against migrants has been the result of varying degrees of xenophobia amongst all racial groups in South Africa. This study proposes the hypothesis that migration results in increased competition over scarce resources in receiving areas, which as a result of xenophobia leads to conflict. Based on the theoretical arguments put forward, the paper aims to determine what policy options for adaptation, mitigation and governance would be most likely to reduce the harmful impacts of climate change on vulnerable regions and groups of people in South Africa and neighbouring countries in order to contain migration and lessen the likelihood of violent conflict. Having identified xenophobia as a spark that could ignite violent inter-group conflict it would be useful to gain some theoretical insight into reducing group prejudice and attaining group cooperation through inter-group contact. It is apparent that there is no single theoretical approach that can be applied to gain a better insight into the complex link between resource scarcity and conflict. The different theories are mutually compatible and each theoretical perspective contributes a partial elaboration to and additional insights into the climate change/conflict hypothesis. There is possibly room for a new theoretical approach to gain a better understanding of the complexity and the uncertainties that are inherent in the study of a mechanism as complex as climate change. South Africa has the responsibility to use its global political influence to promote a shared understanding of responsible behaviour across all societies. Active participation will enable South Africa to guide global negotiations towards outcomes that will lessen the impact of climate change on the most vulnerable countries and populations. In conclusion, possible policies and actions are identified that could support these objectives. Without urgent, appropriate intervention climate change will undermine any efforts to achieve the Millennium Development Goals, and a crippled African continent will be a threat to world security.

APA, Harvard, Vancouver, ISO, and other styles

25

Wang, Guiling 1971. "The role of vegetation dynamics in the climate of West Africa." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/17486.

Full text

Abstract:

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.
Includes bibliographical references (p. 211-224).
The climate of West Africa exhibits significant variability at the time scale of decades. The persistent drought of the past three decades is an example of such variability. This study investigates the role of vegetation dynamics in shaping the low-frequency variability of the climate over West Africa. A zonally symmetric, synchronously coupled biosphere-atmosphere model (ZonalBAM) which includes explicit representation of vegetation dynamics has been developed, and has been validated using observations on both the atmospheric and biospheric climate. The model is then used to study the dynamics of the coupled biosphere-atmosphere system over West Africa. Based on the model sensitivity to initial conditions and the resilience of the coupled system with respect to perturbations, we demonstrate that the coupled biosphere-atmosphere system over West Africa has multiple equilibrium states, with reversible transitions between different equilibria. The two-way biosphere-atmosphere feedback is a significant process in both climate persistence and climate transition. Based on long-term climate simulations using ZonalBAM driven with the observed sea surface temperature (SST) variations, our study shows that vegetation dynamics is a significant process in shaping the climate variability of West Africa. The response of the regional climate system to large-scale forcings is significantly regulated by vegetation dynamics. The relatively slow response of vegetation to changes in the atmosphere is a significant mechanism that acts to enhance the low-frequency rainfall variability. Climate transitions between different equilibria act as another mechanism contributing to the low-frequency rainfall variability - multi-decadal fluctuations can take place as a collective reflection of climate persistence at one equilibrium and climate transition towards another. Vegetation dynamics seems to play an important role in the development and persistence of the current Sahel drought. The most likely scenario for the triggering mechanism of the Sahel drought would involve a combination of several processes including regional changes in land cover as well as changes in the patterns of global and regional SST distributions. However, regardless of the nature of the triggering mechanism, the response of the natural vegetation to the atmospheric changes is the critical process in the development and persistence of the observed drought.
by Guiling Wang.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

26

Sanchez, Alfonso. "The new normal? Climate variability and ecoviolence in sub-Saharan Africa." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2271.

Full text

Abstract:

Climate change presents a wide range of concerns that can jeopardize international security. Among those concerns are neo-Malthusian worries of diminishing natural resources. Predictive models suggest that rainfall and temperature anomalies have the potential to reduce water basins, crop production, increase land degradation among other perils that threaten human security. This concern is particularly true in sub-Saharan Africa given the region’s strong dependence on rain-fed agriculture. Despite strong claims from various world leaders and scientists of a direct climate-conflict nexus, little empirical evidence has been devoted to find a systematic causal pathway of this kind. What is more, the literature not explored the relationship between climate change and low-intensity forms of social unrest. Therefore, contrary to most of the literature that explores a direct climate-conflict relationship, this dissertation contributes to the literature along two lines. First, it explores the relationship between climate change and socio-political unrest. Second, rather than simply assume a direct relationship between climate shocks and conflict, this dissertation examines: a) the effects of climate change on food scarcity, and the impact of that scarcity, in turn, on the likelihood of social unrest and conflict, and b) the effects of climate change on land degradation, that the impact of that degradation, in turn, on the frequency of communal violence.

APA, Harvard, Vancouver, ISO, and other styles

27

James, Rachel Anne. "Implications of global warming for African climate." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:5c49af92-1739-422c-b8f2-e4433c792cc6.

Full text

Abstract:

A 2°C increase in global mean temperature (ΔTg) has been widely adopted as a benchmark for dangerous climate change. However, there has been a lack of research into the implications of 2°C, or any other degree of warming, for Africa. In this thesis changes in African temperature and precipitation associated with 1°C, 2°C, 3°C, 4°C, and beyond are investigated for the first time, using output from 350 climate model experiments: a collection of simulations from international modelling centres (CMIP3), two Perturbed Physics Ensembles (PPEs), and a group of five regional models. The models project temperature and precipitation anomalies which increase in magnitude and spatial extent as global temperature rises, including a wet signal in East Africa, and drier conditions for African rainforests. The models consistently show that the evolution of change with global warming is gradual, even at 4°C and beyond; but the amplitude and direction of precipitation change at each ΔTg increment vary between models and between datasets. The PPEs project precipitation signals which are not represented by CMIP3, in particular a large drying (>0.5 mm day-1 °C-1) of western Africa. There are also important differences between global and regional models, especially in southern and West Africa (>1 mm day-1). Analysis of atmospheric circulation responses suggests that the higher resolution projections are no more credible in this case. Some of the variation between models can be understood as the result of untrustworthy simulations, leading to constraints on the PPEs, and casting doubt on the strong drying of west Sahel; but model evaluation is found to be limited by observations in the case of the Congo Basin. The implications of global warming are different depending on which models are consulted. The findings emphasise that caution should be exercised in the application of climate model data to inform mitigation debates.

APA, Harvard, Vancouver, ISO, and other styles

28

Spires, Meggan Hazel. "Barriers to and enablers of climate change adaptation in four South African municipalities, and implications for community based adaptation." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1018913.

Full text

Abstract:

The focus of this study is on understanding the multiple and interacting factors that hinder or enable municipal planned climate change adaptation, here called barriers and enablers respectively, and their implications for community based adaptation. To do this I developed a conceptual framework of barriers to and enablers of planned climate change adaptation, which informed a systematic literature review of barriers to planned community based adaptation in developing countries. In this framework barriers were grouped into resource, social and physical barriers. I then conducted empirical case study analysis using qualitative research methods in four South African municipalities to understand what barriers and enablers manifested in these contexts. In light of the reflexive nature of my methodology, my framework was adjusted based on my empirical findings, where contextual barriers were found to better represent the empirical results and subsumed physical barriers. I found my framework useful for analysis, but in the empirical cases, barriers and enablers overlaid and interacted so significantly that in reality it was often difficult to separate them. A key finding was that enablers tended to be more about the way things are done, as opposed to direct opposites of barriers. Comparison of barriers and enablers across the case studies revealed a number of key themes. Municipalities struggle to implement climate change adaptation and community based adaptation within contexts of significant social, economic and ecological challenges. These contextual barriers, when combined with certain cognitive barriers, lead to reactive responses. Existing municipal systems and structures make it difficult to enable climate change adaptation, which is inherently cross‐sectoral and messy, and especially community based adaptation that is bottom‐up and participatory. Lack of locally applicable knowledge, funding and human resources were found to be significant resource barriers, and were often underlain by social barriers relating to perceptions, norms, discourses and governance challenges. Enablers of engaged officials, operating within enabling organisational environments and drawing on partnerships and networks, were able to overcome or circumvent these barriers. When these enablers coincided with windows of opportunity that increased the prioritisation of climate change within the municipality, projects with ancillary benefits were often implemented. Analysis of the barriers and enablers identified in the literature and case studies, informed discussion on whether municipalities are able to implement community based adaptation as defined in the literature, as well as the development of recommendations for how municipal planned climate change adaptation and community based adaptation can be further understood and enabled in the future. These recommendations for practice and research include: (a) To acknowledge and understand the conceptual framings of municipal climate change work, as these framings inform the climate change agenda that is pursued, and hence what municipal climate change adaptation work is done and how it was done. (b) The need for further research into the social barriers that influence the vital enablers of engaged officials, enabling organisational environments, and partnerships and networks. (c) To learn from pilot community‐level interventions that have been implemented by municipalities, as well as from other disciplines and municipalities. (d) To develop top‐down/bottom‐up approaches to enable municipal planned climate change adaptation and community based adaptation, that benefits from high level support and guidance, as well as local level flexibility and learning‐by‐doing. (e) To develop viable mechanisms for municipalities to better engage with the communities they serve.

APA, Harvard, Vancouver, ISO, and other styles

29

Sotsha, Kayalethu. "Indicators of household-level vunerability to climate change in three topographically diverse rural villages." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1016204.

Full text

Abstract:

Climate change has become a major concern globally and it clearly exerts a profound influence on the lives of poor rural populations who depend on agriculture for livelihoods.Generally, agriculture is more at risk from weather, pests and diseases than is industry or trade. Furthermore, many farming units are at low levels of development with little technological input in their production systems. This makes them vulnerable to any exposure to climate and environmental variation, given that there is little capacity for the system to adjust to change. Most at risk are the rural poor with low levels of development and limited ability to adapt to and overcome the effects of climate change. Using data from a sample survey of 120 households this study attempts to assess and compare indicators of vulnerability to climate change. The comparison was made at household level between three typical villages, an inland, a river catchment and a coastal village. This idea of comparison arises from the general understanding that different variables affect different regions differently so that the impact of and vulnerability to climate change differs across regions, areas and populations. The data was obtained using a questionnaire that was administered through face-to-face interviews. Given that sensitivity and adaptive capacity of farming systems to climate change is shaped by both socioeconomic and institutional factors, a multiple regression model was used to test the relationship between indicators of vulnerability and household socioeconomic and institutional characteristics. Indicators were selected based on significant statistical relationships. This means that the statistical procedure for selecting indicators involved relating a large number of variables to vulnerability in order to identify statistically significant factors. The results showed reliability of income and reliability of water resources to be good indicators of vulnerability. Many statistically significant variables as well as respective R2 of 0.988 and 0.825 confirm the foregoing. Another indicator was the Simpson index that measures diversification of agricultural production. The results show that vulnerability to climate change was highest for the households near the river and lowest for the inland village. Moreover, the results confirmed that most blacks that are practicing agriculture receive little if any support largely because available resources are highly skewed towards certain farmers rather than others.

APA, Harvard, Vancouver, ISO, and other styles

30

Tesfaye, Melaku. "Atmospheric aerosol distributions and their climatic effects over South Africa using remote sensing observations and regional climate model." Thesis, University of Pretoria, 2013. http://hdl.handle.net/2263/79190.

Full text

Abstract:

Atmospheric aerosols are small solid and liquid particles suspended in the Earth's atmosphere which originate from anthropogenic and natural activities. Unlike greenhouse gases, aerosol particles are relatively short-lived in the atmosphere and exhibit multidimensional heterogeneity with respect to their composition, size, sources, mixing state and the spatio-temporal distributions. The concentration and climatic influences of atmospheric aerosols are much higher closer to their source regions. Therefore, to have a better understanding of the role of aerosols, their distribution and climatic impacts must be understood and quantified on a regional scale rather than on a global‐average basis. There are multiple sources of aerosols/precursor gases in South Africa (SA) which build a complex mixture of atmospheric particulates. This contribution presents a detailed study of aerosol climatology over SA as well as examines the direct radiative and semi-direct climatic effects of individual/total aerosol particles based on their sources. The climatological study has shown that, in terms of aerosol load spatial variation, SA can be classified into three parts: the upper, central, and lower part; which corresponds to high, medium and low aerosol loads. The seasonal variation of aerosol optical signatures shows that the prevailing sources of aerosols are different in each part of SA. The lower part is dominated by particles that are induced from the air mass transport from the surrounding marine environment and other SA/neighbouring regions. The central and upper parts of SA are primarily loaded by windblown mineral dust particles and aerosols that result from anthropogenic/biomass burning activities. Following the aerosol climatological study, using the 12 year (1997 - 2008) runs of the Regional Climate Model (RegCM4), the mass distribution, radiative influences and semi-direct climatic effects of wind-eroded desert dust particles, different species of aerosols that are induced from anthropogenic and biomass burning activities over SA are examined. Investigating the influence of aerosols, based on their sources, is essential to improve the scientific understanding about the two-way interaction and feedback among various species of aerosols, radiation and different climatic variables. This is also important to distinguish the climatic signals of anthropogenic aerosols from that of natural aerosols as well as to devise climate change mitigation strategies. Before employing RegCM4 for these purposes, the model’s performance in reproducing the major observational features of aerosol optical fields over SA was evaluated. Among various semi-direct climatic influences of aerosols, this study examined their effects on: surface temperature, surface sensible heat flux, net atmospheric radiative heating rate, hydrological variables (in terms of cloud cover and cloud liquid water path), boundary layer, surface pressure and surface wind fields. The study also assessed the dependency of aerosols’ semi-direct effects on seasonal variation of meteorological parameters as well as its reliance on atmospheric aerosol distributions and properties. Overall, the semi-direct effect assessments delivered not only an important contribution towards the understanding of the interaction and feedback between different types of aerosols-radiation-climate (at a regional level), but also offered insightful information about the mutual interrelationships among different climatic feedbacks. Among different aerosol species in SA, this study critically underscores that the wind-eroded desert dust particles have a dominant climatic signal in SA. Therefore, wind-eroded desert dust particles are of high importance and need to be incorporated in climate change studies over South Africa. Additionally, the dominance of dust particle climatic signals perhaps requires some attention from governmental or non-governmental environmental organizations which are working in and around South Africa: at least in terms of making some strategic plans on how to reduce the dust production and dispersion.
Thesis (PhD)--University of Pretoria, 2013.
Geaography, Geoinformatics And Meterology
PhD
Unrestricted

APA, Harvard, Vancouver, ISO, and other styles

31

Morahanye, Mokhantso Lilian. "Investigating adaptation strategies to climate change by smallholder farmers : evidence from, Lesotho." Thesis, University of Fort Hare, 2017. http://hdl.handle.net/10353/5807.

Full text

Abstract:

In Lesotho, agriculture is the dominant activity and involves crop and livestock production, range management and forestry activities. The current climatic variability in the country has caused decline in food production as result of increased dry spells, frequency of droughts and erratic rainfall. These climatic events are expected to have a significant impact on the livelihoods of the smallholder farmers. In combatting the harmful effects of climate change, smallholder farmers in Lesotho have employed various adaptation strategies based on their local knowledge and limited means. While these strategies may not be optimal they obviously constitute the basis for potentially effective improved technologies which can be developed and communicated through an efficient extension system, hence the need to precisely identify them and understand the factors that affect their choice. The main objective of this study was therefore, to identify the adaptation strategies and investigate the factors influencing smallholder farmers’ choice of those adaptation strategies. The study made use of multi-stage stratified sampling technique to select 160 respondents across four agro-ecological zones (lowlands, highlands, foothills and Senqu River Valley) in Leribe and Mohales’Hoek districts of Lesotho. Primary data for the study were collected using semi - structured questionnaire assisted with interview schedules administered on the respondents. Data collected were analysed using descriptive statistics and the multinomial logistics regression model. The results show that there are more males than females, majority of the respondents’ attained primary education, and older people dominate the smallholder farming system. The adaptation strategies used in MNL model were soil and water management, crop management and livestock management. The results further revealed that soil and water management strategies were the most adopted climate change strategies amongst smallholder farmers. It is understood that marital status, age and gender, income, land tenure, crop grown, extension services, and agro-ecological zones are the determinant factors influencing the choice of the adaptation strategies. This study concludes by recommending that smallholder farmers should be sensitised about climate change and both government and non-government organisations working on climate change related issues should direct their attention to rural communities to ensure effective response to climate change.

APA, Harvard, Vancouver, ISO, and other styles

32

INDEJE, MATAYO. "PREDICTION AND NUMERICAL SIMULATION OF THE REGIONAL CLIMATE OF EQUATORIAL EASTERN AFRICA." NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20000810-143914.

Full text

Abstract:

INDEJE, MATAYO. Prediction and Numerical Simulation of the Regional Climate of Equatorial Eastern Africa. (Under the direction of Dr. Fredrick H. M. Semazzi.). The objective in this investigation was to provide a better understanding of the mechanisms and physical processes responsible for climate variability over the equatorial eastern Africa, and explore potential for short-term climate prediction. Both statistical and numerical methods have been employed in this research. Application of cluster analysis yields 8 and 9 homogeneous climatic zones respectively for the variability of the annual and seasonal rainfall. Regions that are prone to drought or floods during the different phases of El Niño-Southern Oscillation (ENSO) are delineated. Positive rainfall anomalies occur in much of the region during March-May (MAM) and October-December (OND) of the ENSO(0) years and negative anomalies dominate during the following ENSO(+1) years. These rainfall patterns are useful for short-term climate monitoring over the region. The relationship between the Quasi-Biennial Oscillation (QBO) in the lower stratospheric zonal winds and the long-rains of MAM is more significant in lagged than in simultaneous, with the most distinct relationships occurring over the western parts of the region. The QBO-index explains about 36% of the seasonal rainfall variance. There is a 60/63 percent likelihood for the occurrence of above/below normal rainfall during the westerly/easterly phase of the QBO-index. The NCAR Regional Climate Model (RegCM2) simulations have demonstrated the added value of the nesting approach in improving regional climate simulations. The model reproduces the observed characteristics of the Turkana low-level jet. The study has shown the importance of orographic forcing, the large-scale background monsoon flow and depth of the channel in the development and maintenance of the jet. Thermal and frictional forcing play equivalent roles as that of the large-scale winds in the formation of the jet. The identified regions of strong winds associated with the jet are important to the safety in the aviation industry and are also potential for alternative renewable energy resources in the form of wind energy. Large-scale orography is the most important factor. Divergence and anticyclonic vorticity partly explains the observed split in the jet cores. The dynamics of the flow in the channel and the dry conditions observed over the wider part of the valley is in partly explained by the Bernoulli theorem as applied to barotropic steady and non-viscous flows. Air-sea interaction phenomenon over the Indian Ocean, and the latitudinal location and intensity of the large-scale Walker and Hadley circulations are the main physical mechanisms responsible for the climate variability over the region during the wet and dry years. Abundant rainfall is associated with the presence of a midtropospheric cyclonic wind shear across the equator, and a negative vertical wind shear. Likewise, dry conditions are associated with the presence a strong westerly/southerly wind anomaly that occurs throughout the troposphere. Short-term climate prediction models developed in this study are capable of skillfully reproducing the space-time evolutions and distribution of the seasonal rainfall over the region, and specifically the observed floods that occurred during the 1997 ENSO year. Preliminary application of the RegCM2 in the prognostic mode successfully produces a 3-months projection of the extreme seasonal anomalies associated with the 1997 ENSO event. These models can be exploited further in operational short-term climate prediction over equatorial eastern Africa.

APA, Harvard, Vancouver, ISO, and other styles

33

Long, Shelby K. "The Effect of Climate Change on Food Security in Sub-Saharan Africa." Scholarship @ Claremont, 2015. http://scholarship.claremont.edu/cmc_theses/1070.

Full text

Abstract:

The purpose of this thesis is to examine the projected future changes in the global and Sub-Saharan Africa climate. These changes are expected to have varying effects depending on the region of the globe being examined. Sub-Saharan Africa is expected to be one of the most vulnerable regions in the future because of the already-variable and unpredictable climate. Population growth and lack of financial and informational resources further exacerbates the climate problems, making it even more difficult for African farmers to respond to their changing environment. In order to respond to these climate changes within an already dry and nutrient-lacking environment, farmers must be given the necessary adaptation information and aid from outside investors. However, without the proper information available to investors, regarding future expectations about precipitation, temperature, extreme weather events, soil nutrients, and available adaptation strategies, investors cannot efficiently allocate capital or other forms of aid. Therefore, I stress the importance of developing accurate climate models on a regional scale that investors can use to better allocate aid. Each region is affected in very different ways by the climate as a result of local topographical factors and global factors, such as the Intertropical Convergence Zone. Therefore, tools, such as models and simulations must be able to take these factors into account in order to accurately project future changes. This thesis examines a wide range of existing literature in the area of climate change and food security on both a global and regional scale. I investigate the current and future climate of Sub-Saharan Africa, as well as the farming culture, in order to provide an in-depth understanding of the various factors that are interacting. Although many steps have been made to develop models and provide aid to Sub-Saharan Africa farmers, the lack of food security is only expected to become worse as the environment becomes harsher on food crops. Therefore, in order to respond to the expanding population and harsher farming environment, farming adaptations must continue to be intensified.

APA, Harvard, Vancouver, ISO, and other styles

34

Adole, Tracy. "Land surface phenology of Africa, its drivers and relationship with climate variability." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/426892/.

Full text

Abstract:

The study of vegetation phenology is very important because it is a sensitive indicator of climate changes. In the last few decades, phenological studies have focussed on using satellite sensor data because of it benefits. Nevertheless, despite being home to the second-largest area of rainforest and wetlands, and the largest area of savanna in the world with a diverse range of vegetation types, Africa is still one of the most poorly studied regions in the world. Very little is known about its vegetation phenology and it drivers. Hence, this study aimed (i) to identify major research gaps by providing a synthesis of studies of related Africa's vegetation phenology and classify them based on the methods and techniques used (ii) to provide seasonal vegetation phenological pattern of the major land cover types in different geographical sub-regions in Africa using medium spatial resolution data (iii) to understand the recent trends in Africa's vegetation phenology over the period 2001 - 2015 (iv) to understand the influence of land cover changes on LSP trends and (v) to investigate the relationship between vegetation phenological pattern and climatic factors. Significant increases in the number of phenological studies in the last decade were observed, mostly remote sensing, whereas ground based studies occurred rarely in the continent. Even more evident was the lack of phenological networks in the continent. In addition, a more detailed and up-to-date characterisation of Africa's LSP was reported. Furthermore, longer vegetation growing season and the influence of land cover changes were observed. Relating to the climate-LSP relationships, this study showed a wider spread of pre-rain green-up over Africa than previously reported and the localised post-rain green-up. The major climatic drivers of LSP parameters in the continent was also reported. In general, therefore, these results alongside recommendations can significantly improve our understanding of vegetation-climate interactions, and ultimately improve vegetation phenological and climatic studies in Africa.

APA, Harvard, Vancouver, ISO, and other styles

35

Mdoka, Marshall Lison. "The role of soil moisture on summer climate simulations over southern Africa." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20344.

Full text

Abstract:

This study aims to increase our perspective of the responses of Southern African climate to soil moisture forcings by drying or moistening the land surface using a regional climate model version 3, RegCM3. The sensitivity and response capabilities to soil moisture perturbations of the model are investigated. This includes identification of regions that may be influenced differently by antecedent soil moisture conditions as well as understand the implications of soil moisture conditions on frequency and intensity of rainfall. Exploratory analyses of soil moisture retention and comparison of climate model parameters with available observations or re-analysis data is done. The study then seeks out the large-scale atmospheric forcings under which the regional climate explicitly responds to perturbations in soil moisture using self-organising map technique. To investigate these underlying processes of atmosphere-soil moisture interactions a series of RegCM3 model experiments utilizing wet, dry and normal soil moisture conditions were designed. The experiments are based on changing the soil moisture field capacity in the RegCM3. The control simulations are run with RegCM3 nested in NCEP/NCAR reanalysis 2 data and using Emanuel convective scheme for the selected six summers (dry seasons - 1991/92, 1994/95 and 1997/98; wet seasons - 1995/96, 1996/97 and 1998/99). September to March simulations are performed with August as the spin-up month. The respective dry and wet soil moisture perturbation simulations are then initialised at field capacities of 25% (wilting) and 75% (saturation) within the land surface model, Bio-sphere Atmosphere Transfer Scheme. From the sensitivity studies, anomalously dry (wet) conditions have positive feedbacks with similar dry (wet) synoptic forcings of the regional climate. Anomalous dry forcing persists for longer and exacerbates the changes in the regional anticyclonic circulation especially during a drought or dry period. Soil moisture perturbations mostly affect the lower troposphere. Surface variables analysed especially surface temperature show strong responses to the soil moisture perturbations under all synoptic forcings but rainfall characteristics are strongly influenced by large-scale synoptic circulations. However, in some areas over southwestern parts of the region a weak feedback which can be either positive or negative depending on geographical and climatological setting has been detected.

APA, Harvard, Vancouver, ISO, and other styles

36

Rapolaki, Ramontsheng Sakia. "A numerical simulation of tropical storm Chedza over south-eastern Africa." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22953.

Full text

Abstract:

Widespread flooding over parts of Malawi, Mozambique, and Madagascar occurred in January 2015. An impact assessment by the World Bank indicated huge damage to property, infrastructure, and agriculture over several regions in south-eastern Africa. The flooding was associated with tropical storm Chedza that developed in the Mozambique Channel on 11 January 2015. This study investigates the atmospheric circulation and potential mechanisms responsible for the heavy rainfall event that occurred between 11 and 17 January over Mozambique and Malawi using the Weather Research and Forecasting (WRF) model, the Global Forecast System (GFS) atmospheric reanalysis, satellite derived rainfall and wind data, and station rainfall data. Tropical Rainfall Measuring Mission (TRMM) rainfall estimates and rainfall station data indicated that southern Malawi and northern Mozambique experienced the majority of rainfall during the early stages of tropical storm Chedza while Madagascar experienced heavy falls when tropical storm Chedza tracked over the island on January 17. Furthermore, analysis of the station data revealed that the heavy rainfall over Mozambique occurred between 11 and 13 January with some stations recording about 80 % of their total January 2015 rainfall as resulting from this event. The WRF model run of the event indicated a low level easterly to southeasterly onshore flow over southern Mozambique that interacted with a northwesterly monsoonal flow to westerly flow along the northern flanks (periphery) of the storm in the northern Mozambique Channel, leading to surface moisture flux convergence in the regions of heavy rainfall. Furthermore, moisture from the southwest Indian Ocean was advected into the region during the heavy rainfall. It is suggested that multiple favourable factors which included strong moisture fluxes from the southwest Indian Ocean and equatorial South Indian Ocean, near surface convergence over the areas of heavy rainfall, and strong uplift acted together to create favourable conditions for the development of tropical storm Chedza and the associated heavy rainfall.

APA, Harvard, Vancouver, ISO, and other styles

37

Pearce, Helen Elizabeth. "East African rainfall : classification of rain producing systems : a modelling and observation study." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:d5bb4c4c-6e5e-40d4-8a65-b3002277b550.

Full text

Abstract:

The study of anthropogenic climate change is a research area of vital importance for the coming decades, with rainfall change and variability expected to be keenly felt in vulnerable regions of the world, including Africa. The focus of this study is daily rainfall during the short rains season over East Africa from October to December, which has one of the most coherent increasing rainfall projections in the Coupled Model Intercomparison Project (CMIP) dataset. This thesis aims to examine the fidelity of coupled climate models over an East African domain, with the question approached through focus on the daily (rather than monthly) rainfall field. The self-organising map is used as a clustering tool to establish contemporary characteristics of daily rainfall events in reanalysis (ERA-40) and satellite (TRMM) rainfall datasets between 1971-2000 and 1998-2010 respectively for the East African short rains. Moisture flux divergence is found to be the circulation parameter that is most closely related to the presence of rainfall events or dry conditions over East Africa. Coupled climate models are poor at replicating the daily rainfall field over the domain. A key result of the analysis is the consistent overestimation of daily rainfall by climate models for days where dry conditions of suppressed convection should prevail. In contrast, the moisture flux divergence field maps well to dry nodes for days of the self-organising map array for the models. Dry days are associated with widespread anomalous moisture flux divergence and rainfall events with co-located anomalous moisture flux convergence. This is in agreement with the moisture flux divergence field in the ERA-40 dataset; it is the rainfall field where there is disagreement for days of suppressed convection. Twenty to thirty-five percent of the projected rainfall increase towards the end of the twenty-first century results from an increase in the proportion of days assigned to nodes of suppressed convection in six of the seven models and the ensemble mean. There is an accompanying projected rainfall increase associated with days assigned to these nodes. Such days in the 2090s are characterised by projected increased strength moisture flux divergence over East Africa. Given that the moisture flux field was more successfully simulated in the coupled models under contemporary conditions than the daily rainfall field, this suggests that rainfall projections under a high emissions scenario at the end of the twenty-first century are overestimated and that an important part of the key increase in the projected rainfall may not be real.

APA, Harvard, Vancouver, ISO, and other styles

38

Jilesen, Robin P. "Climate Change and Migration to South Africa : Exploring the Role of Climate- and Environment-Related Adversities in Mobility Decision-Making." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/78346.

Full text

Abstract:

This dissertation examines the impacts of climate- and environment-related stress on migration from other sub-Saharan African countries to South Africa, which is a prominent destination for migrants. It describes the factors and processes that influenced migration decisions and provides insights into the experiences of these individuals before, during, and after migration. Data was gathered through semi-structured interviews with migrants from several sub-Saharan African countries now residing in South Africa’s Gauteng province, as well as key informants with expertise on migration, climate change, and environmental problems in Africa. Additional information was gathered from secondary material, such as reports, grey literature, and academic publications. The principle finding is that, although climatic and environmental stresses are not the primary drivers for migration to South Africa, they play a clear contributing role, both directly and indirectly. The direct contributions included drought, land degradation, floods, and erratic rainfall. Such environmental drivers for migration did not occur in isolation, instead, they were found to frequently intersect with various economic, political, social, and demographic drivers. Indirect contributions were largely through negative impacts on economic and political factors that became direct drivers for migration. Whether people respond to these adverse conditions by migrating depends on a number of factors that can be divided into three areas: intervening obstacles and facilitators of migration, personal and household characteristics, and expectations of the destination. Although some migrants in the re-search sample had experienced improvements in their quality of life since they had migrated to South Africa, the majority of migrants indicated that their lives were still characterised by insecurity, precariousness, and hopelessness.
Dissertation (MSocSci (Development Studies))--University of Pretoria, 2020.
Anthropology and Archaeology
MSocSci (Development Studies)
Unrestricted

APA, Harvard, Vancouver, ISO, and other styles

39

Söderström, Ellen. "Men, masculinities and climate change : A study of climate change impacts in cases from Greenland, Australia Peru and South Africa." Thesis, Linnéuniversitetet, Institutionen för samhällsstudier (SS), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-44709.

Full text

Abstract:

‘Climate change is not gender neutral’ is a statement that has gained more recognition within the climate change debate over the last decade. This has resulted in a new field of research called gender and climate change. The mainstream gender and climate change debate has earlier almost exclusively focused on women’s vulnerability. A brief reading of the literature clearly shows that men are rarely observed in this context. The objective of this thesis is to broaden the understanding of the relation between gender and climate change by bringing men into the discussion. I have selected four cases/countries where existing research on men’s gendered experiences of climate change are mentioned. These take place in Greenland, Australia, Peru and South Africa. The result show five common findings between the cases: gendered responsibilities, changing traditional gender roles, psychological impacts, alcohol consumption and violence against women. The concept hegemonic masculinities is utilized as a framework used to understand why men are negatively affected by climate change. Masculine norms of attitudes and behavior identified in the multiple case studies are invulnerability and unwillingness to seek help. The analysis show that in times of climate variability can masculine norms be damaging for both men and women. A second analytical framework, the gender transformative approach brings the analysis to critically reflect upon masculinities and climate change as functions of power. From this perspective this thesis concludes that the gender and climate change discourse needs to move beyond a focus on women’s vulnerabilities, which divide the world into two classes: women as victims and men as perpetrators. This approach rather urge for a focus on the structures of power and domination within laws, behaviors and institutions that generates injustices.

APA, Harvard, Vancouver, ISO, and other styles

40

Obarein, Omon A. "Relative Long-term Changes in West African Rainfall Components." Kent State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=kent1598884754345658.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Ndlala, Noluthando. "Remote sensing drought impacts on wetland vegetation productivity at the Soetendalsvlei in the Heuningnes Catchment, South Africa." University of Western Cape, 2021. http://hdl.handle.net/11394/8329.

Full text

Abstract:

>Magister Scientiae - MSc
This work aimed at assessing the response of wetland vegetation productivity to the 2014-2017 climate-induced drought at the Soetendalsvlei wetland system in the Western Cape province of South Africa. To achieve this objective, firstly a literature review on the progress of remotely sensed data applications in assessing and monitoring wetland vegetation productivity was conducted. The review elaborates on the role of remote sensing in monitoring and assessing wetland vegetation productivity, with a detailed discussion of the climate change and variability impacts on wetland vegetation productivity. Accurate assessment results are produced when suitable processing techniques are selected as well as appropriate spatial and spectral resolution for extracting spectral information of wetland vegetation productivity. Secondly, wetland vegetation changes and productivity status was assessed using multi-temporal resolution Landsat series imagery and Normalized Difference Vegetation Index (NDVI) during the wet and dry seasons for the period between 2014 and 2018.

APA, Harvard, Vancouver, ISO, and other styles

42

Singh, Karishma. "Population dynamics of the Zuurberg Cycad and the predicted impact of climate change." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1012857.

Full text

Abstract:

Cycads first appeared about 300 million years ago and historical data indicates that they survived fluctuations of global temperature and carbon dioxide concentrations and reached peak abundance during periods where temperature and carbon dioxide concentrations were much higher than the present conditions as well as the predicted increased levels. With Africa being one of the most vulnerable regions to climate change and in the absence of an evaluation of predicted impacts of climate change on cycads, this study aims to contribute to our understanding of responses of Encephalartos longifolius to increased temperature. Encephalartos longifolius (Jacq.) Lehm is an Eastern Cape endemic and like most cycads has been around for millions of years with very little change to its basic structure. Photosynthetic rates showed E.longifolius seedlings have C3 photosynthesis and even under stress they do not switch over to CAM photosynthesis. The photosynthetic rates of seedlings showed a typical C3 -plant type response under elevated carbon dioxide levels. Increased temperatures could be detrimental to the species but coupled with elevated carbon dioxide levels the growth of Encephalartos longifolius are postulated to outweigh the negative impacts of increased temperatures. Whilst climatic conditions in the Eastern Cape might not impact the abundance of Encephalartos longifolius, the species however is declining rapidly to the present near-threatened status. Demographic studies revealed a high percentage of juvenile numbers in the wild; however juvenile plants are impacted on by animals thereby jeopardizing their survival. Adult plants are heavily impacted on by animals; this reduces the probability of new offspring being produced. Cycads are also very slow - growing which is the primary cause of their ruin in the wild. Encephalartos longifolius grows at just over approximately 1 cm per year with growth being more rapid in the juvenile plants. Once juvenile plants reach approximately 60 cm they stop growing in diameter but only get taller. Seed germination is also a very slow process with an optimum temperature of 28°C and a growth medium of at least 50 percent moisture. Regardless of the Eastern Cape predicted to become the hottest province in South Africa as a result of climate change, cycads will be able to adapt to the changing environment and conservation plans should focus on animal and human impacts that are the major force causing decreasing abundance of Encephalartos longifolius in the wild.

APA, Harvard, Vancouver, ISO, and other styles

43

Sibanda, Patience. "Climate change mitigation and resilience by four major supermarkets in East London, South Africa." Thesis, University of Fort Hare, 2017. http://hdl.handle.net/10353/5406.

Full text

Abstract:

Climate change is a human development challenge. Its negative impacts have the potential to reverse the human development gains made in Africa. South Africa, just like many other countries in the Global South, is being negatively affected by climate change. The country`s economy is largely dependent on agriculture, extractive industries and manufacturing, all of which are vulnerable to climate change in different ways. This vulnerability means different public and private stakeholders must institute sustainable climate change mitigation and adaptation measures so as to ameliorate climate change impacts. Gradually transforming to an environmentally friendly ‘green economy’ and the reduction of greenhouse gas emissions are some of South Africa’s climate change mitigation priorities. Just like the public sector, the private sector has a major role to play in this transition to a low carbon economy through minimising its carbon emissions in their operations. Against this background, this qualitative research examines the role played by four major supermarkets (Shoprite, Spar, Pick n Pay and Woolworths), in climate change mitigation and resilience building. It does so through an appraisal of their mitigation and resilience programs. The four supermarkets were purposively selected in East London, Eastern Cape. Data collection combined heavy reliance on desktop discourse analysis with field interviews in the form of purposively sampled key informant interviews. The results show that the four major supermarkets are implementing a variety of climate change mitigation and resilience strategies. These include reduction of greenhouse gas emissions, prioritisation of renewable energy, recycling and environmentally friendly packaging, promotion of sustainable ways of farming and improved fuel efficiency in their transport systems. In terms of policy improvement, the study recommends that there is need for supermarkets to learn from each other’s’ climate change mitigation initiatives so as to advance South Africa’s ‘green economy’ agenda.

APA, Harvard, Vancouver, ISO, and other styles

44

von, Uexkull Nina. "Climate, Conflict and Coping Capacity : The Impact of Climate Variability on Organized Violence." Doctoral thesis, Uppsala universitet, Institutionen för freds- och konfliktforskning, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-300183.

Full text

Abstract:

Understanding the conflict potential of climate variability is critical for assessing and dealing with the societal implications of climate change. Yet, it remains poorly understood under what circumstances – and how – extreme weather events and variation in precipitation patterns affect organized violence. This dissertation suggests that the impacts of climate variability on organized violence are conditional on specific climate patterns, the sensitivity of livelihoods, and state governance. These theoretical conjectures are subjected to novel empirical tests in four individual essays. Three essays investigate the relationship between climate variability and communal and civil conflict through sub-national quantitative analysis focusing on Sub-Saharan Africa. The fourth essay sheds light on causal mechanisms leading to participation in land-related conflict based on interview material on 75 ex-participants in violence from Mt. Elgon, Kenya. Essay I suggests that the exposure of vulnerable agricultural livelihoods to sustained drought increases the risk of civil conflict violence. Essay II indicates that rainfall anomalies increase the risk of communal violence, an effect which is amplified by political marginalization. Essay III finds support for the proposition that volatility in resource supply increases the risk of communal conflict over land and water in remote regions, which tend to have limited state presence. Essay IV proposes that individuals depending on agriculture are prone to participate in land-related conflict as they face impediments to leaving a conflict zone, and additionally have high incentives to partake in fighting for land. Taken together, the dissertation furthers our understanding of the specific economic and political context under which climate variability impacts armed conflict. This knowledge is important for conflict-sensitive adaptation to climate change and conflict prevention efforts.

APA, Harvard, Vancouver, ISO, and other styles

45

Pryor, John W. "Framework Integrating Climate Model, Hydrology, and Water Footprint to Measure the Impact of Climate Change on Water Scarcity in Lesotho, Africa." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7353.

Full text

Abstract:

Water scarcity is a problem that will be exacerbated by climate change. Being able to model the effect of climate change on water scarcity is important to effectively plan the use of future water resources. This research integrated the Soil and Water Assessment Tool (SWAT), climate model, and water footprint analysis to measure the impact of climate change on future water scarcity. This was achieved through two objectives. The first objective was to create a modeling framework that links the output from climate model to SWAT and combined streamflow outputs from SWAT with water footprint analysis to measure how climate change will impact water scarcity of a river basin. This was accomplished through creating a SWAT model within ArcMap and inputting a topographic, soil, land use, and weather data. Climate Forecast System Reanalysis (CFSR) data were used in lieu of observed weather data due to a lack of available data. SWAT-CUP (Calibration and Uncertainty Program) was used to calibrate two upstream streamflow gauges, then calibrate and validate a third streamflow gauge at the outlet of the Senqu basin in Lesotho. The two upstream streamflow gauges were calibrated from 1986 to 2002. The downstream streamflow gauge was calibrated from 1985 to 2002 and validated from 2003 to 2013. Three Regional Climate Models (RCM), ICHEC-EC-EARTH, MIROC-MIROC5, and CCCma-CanESM2 were downloaded from the Coordinated Regional Downscaling Experiment (CORDEX) dataset. Each RCM was downloaded with two different Coupled Model Intercomparison Project (CMIP5) Representative Concentration Pathways (RCP), RCP 4.5 and RCP 8.5. The RCMs were bias corrected using a cumulative distribution function mapping technique. These RCMs as well as an average of the RCMs were used as input for the SWAT model to generate future streamflow outputs. The streamflow outputs provide the future blue water availability of the Senqu River. The results showed an overall decrease in streamflow in both RCPs. The second objective was to apply the framework to Lesotho and use the information from the ArcSWAT model and data from the Blue Water Footprint analysis to measure the future potential Blue Water Scarcity of Lesotho. This was accomplished through the Blue Water Footprint of Lesotho generated from the 5th National Blue Footprint analysis. The annual blue water scarcity was calculated as the ratio of the Blue Water Available to Blue Water Footprint. Three approaches were adopted to analyze the water scarcity of Lesotho. The first approach used the national Blue Water Footprint in the water scarcity calculation to investigate the worst-case scenario. The second approach used the modified blue water footprint based on the population living within the Senqu river basin. The third approach used a modified blue water footprint that accounted for the projected population growth of Lesotho. The results of scenario 1 showed there was moderate water scarcity in a period of four years in climate scenario of RCP8.5. The results of scenario 3 showed there were multiple cases of water scarcity in both RCP 4.5 and RCP 8.5 with two years of severe water scarcity. This research is limited by data availability and the results for Lesotho could be improved by accurate dam data and the fine scale water footprint analysis. The modeling framework integrating climate model, hydrology, and water footprint analysis, however, can be applied to other remote places where limited data are available.

APA, Harvard, Vancouver, ISO, and other styles

46

Madzivhandila, Thanyani Selby. "The effects of climate change on household food production in rural Makhado Local Municipality, Limpopo Province." Thesis, University of Limpopo, 2015. http://hdl.handle.net/10386/1548.

Full text

Abstract:

Thesis (Ph.D. (Administration)) -- University of Limpopo, 2015
The thesis of this study is that food production systems for self-provisioning have historically constituted the backbone for survival and life-support in rural South Africa. Colonialism and apartheid capitalism bore harsh effects on the food production life support systems. However, these effects pale into insignificance compared to the present devastation of the food production systems associated with climate change. The contribution of rural South Africa towards climate change is at all scale negligible because poor people hold limited capacity to produce the deleterious gas emissions that allegedly causes global warming. However, the poor are disproportionately exposed to the adversarial effects of climate change and their food production systems have demonstrated beyond doubt that they cannot cope with stressors occasioned by climate change. Government policy and measures continue to be inadequate and inaccessible for rural households that produce for self-provisioning. The thesis further demonstrate that scientifically–based intervention measures adopted among rural poor in developing countries are viewed as alien and therefore not wholeheartedly adhered to by the users. The thesis points to this discrepancy to illustrate that the value systems among the rural population in South Africa describe changes in their food production in terms of climatic conditions that are, according to their belief systems, avoidable consequences of people’s conduct of life outside tradition, religion and so on. It engages a nascent argument relating to the failure of private and public scientifically-generated intervention measures within developing countries’ rurality, which is ironically exacerbated by the apparent inappropriateness and, often, destructiveness vi of the Green Revolution Technologies. As such interventions fail, the thesis points, they create skeletons of evidence, that appear to corroborate the traditionalist belief systems about the locus of causes of change in climatic conditions being extra-terrestrial as a consequence of people’s misconduct of life. The study investigates the effects of climate change on household food production systems in rural Makhado Local Municipality. 30 villages are used for this study in both households questionnaire survey, interview of the key informants and observation of different patterns of production process, geo-spatial features and current settlements patterns. The data analysis results reflect that different households within the municipality experiences variety of effects of climate change. Furthermore, the climatic conditions which consisted of enough reliable precipitation during food production stages have declined; rather in the post-1990 period, the area have been experiencing continuous heatwaves and drought which destroyed household’s crops and livestock. Using the normative and historical research designs the study found that the situation within villages has changed drastically because of climate change when comparing the conditions preand post-1990. The deliberate adoption of the historical design was crucial given that the thesis mission was to highlight the discrepancies in the so-called modern systems versus the traditionalist philosophies that continue to dominate the thinking and action rural populations in most developing countries. Equally, the historical design provides unquestionable possibility of applying appropriate research techniques to contextualize the research problem under investigation. Indeed, this manoeuvre has always been an important part and parcel of the research design and methodology because the thesis vii had to adopt a longitudinal research orientation through an appropriately designed data collection tool, specifically the questionnaire and interview schedule. From a philosophical perspective, the thesis demystifies the thinking that the so-called scientifically-generated interventions against climate change could resolve the attendant challenges, inclusive of food production. That is, it insinuates that appropriate research is needed for developing countries rurality in order to find intervention measures that are a product of the evolution of traditionalist value systems. Tacitly, the thesis challenges the statist and private sector habits of always parachuting the so-called scientifically generated solutions to climate change.
University of Limpopo Research Administration Department.

APA, Harvard, Vancouver, ISO, and other styles

47

ACHEAMPONG, MICHAEL. "IMPROVING FOOD SECURITY IN SUB-SAHARAN AFRICA WHILE LIMITING PRODUCTION IMPACTS ON CLIMATE." Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-15614.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Itambie, Achakie Cletus. "Rock magnetic and geochemical signals of late Quaternary climate variability over northwest Africa." lizenzfrei, 2008. http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000111701.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

LaJoie, Mark R. "The impacts of climate variations on military operations in the Horn of Africa." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Mar%5FLaJoie.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Von, Diest Saskia Gudrun. "Responses of Venturia inaequalis to sanitation and regional climate differences in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86217.

Full text

Abstract:

Thesis (PhD(Agric))--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The apple industry in South Africa currently relies entirely on chemical fungicides to control apple scab, caused by Venturia inaequalis. In this dissertation, alterative management strategies against V. inaequalis were tested for the first time in South Africa. New information on the behaviour of the sexual winter phase of V. inaequalis in different climatic conditions was found and sources of asexual inoculum overwintering in apple orchards were identified. The effect of leaf shredding on fruit and leaf scab incidence and severity was tested against a non-shredded, non-sprayed negative control, a positive control that followed a commercial fungicide programme and a combined treatment of a commercial fungicide programme with leaf shredding, from 2010 to 2013. Reductions in fruit and leaf scab incidence and severity in the leaf shredding treatment were significantly lower compared to the negative control. Quantitative real-time polymerase chain reaction (qPCR) of airborne ascospores trapped using volumetric spore traps was used to measure the reduction in airborne ascospores in the shredded plots, and confirmed the efficacy of shredding found by comparing scab incidence and severity on fruit and leaves. Shredding twice during leaf-drop increased the efficacy of the treatment. Results indicate that leaf shredding should be integrated into scab management strategies in future. However, practical considerations unique to South African orchards, e.g. timing of leaf shredding relative to leaf-drop and orchard layouts, need to be addressed. Pseudothecial densities (PD, number of pseudothecia per fertile lesion) and ascal densities (AD, number of asci per pseudothecium) were compared between in Koue Bokkeveld (KB), a cold winter region, and Elgin (EL), a warm winter region experiencing climate warming, in 2012 and 2013. Scabbed leaves were detached during leaf-drop and overwintered in their region of origin and in the other region. The PD in leaves collected in KB and overwintered in KB was significantly higher than for leaves collected in EL and overwintered in EL, and leaves collected in KB and overwintered in EL. These results agreed with what was expected, as temperature during pseudothecial formation (i.e. the first four weeks after leaf-drop) was significantly lower in KB than in EL. However, the PD for leaves collected in EL and overwintered in EL did not differ significantly from EL leaves overwintered in KB. AD values in all treatments did not differ significantly from one another. Results suggest that factors other than temperature may be involved in controlling PD, e.g. the EL population may include strains not present in the KB population, with higher optimal temperatures for pseudothecial formation. Apple buds and pygmy apples were collected and tested for presence, number and viability of conidia in 2010, 2011 and 2012. Pygmy apples are small, late season fruit that remain attached to the tree throughout winter, especially in regions with warmer winters where trees do not experience sufficient chilling to complete dormancy. High conidial numbers were found on outer bud tissue and low numbers on inner bud tissue, but viable conidia were only found on inner bud tissue, using microscopy, and generally in orchards with high scab levels in the previous season. Molecular methods using PCR-RFLP and qPCR confirmed the presence of high amounts of V. inaequalis DNA in outer bud tissues, although calculated conidial amounts were higher than data obtained when using microscopy, which could indicate presence of mycelia not detected during microscopic examination. Higher numbers of conidia with higher percentage viability were found on pygmy apples, which are a more likely source of asexual inoculum in South African apple orchards than the low number of viable conidia on inner bud tissue.
AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse appelbedryf is tans afhanklik van chemiese swamdoders vir die beheer van die appelskurf patogeen, Venturia inaequalis. In hierdie proefskrif is alternatiewe bestuurstrategiëe vir die eerste keer in Suid-Afrika ondersoek. Nuwe inligting te opsigte van die gedrag van die geslagtelike winterfase van V. inaequalis, is onder verskillende klimaatstoestande ingewin en bronne van die oorwinterende ongeslagtelike inokulum in appelboorde, is identifiseer. Die invloed van blaarversnippering op die voorkoms en erns van appelskurf op vrugte en blare, is vanaf 2010 tot 2013 ondersoek en met ŉ negatiewe kontrole (onversnipperde blare sonder spuitprogram), ŉ positiewe kontrole (ŉ kommersiële swamdoderspuitprogram is gevolg) en gekombineerde behandelings (kommersiële swamdoderspuitprogram en blaarversnippering) vergelyk. Daar was ŉ betekenisvolle verskil in die voorkoms en erns van skurf op vrugte en blare met blaarversnippering teenoor die negatiewe kontrole. Kwantitatiewe intydse polimerase kettingvermeerderingsreaksie (kPKR) van luggedraagde askospore, vasgevang in volumetriese lokvalle, is gebruik om die afname van luggedraagde askospore in versnipperde behandelings te meet. Die doeltreffendheid van versnippering as behandeling, is bevestig deur die voorkoms van appelskurf te vergelyk met die ernstigheidsgraad daarvan op vrugte en blare. Die uitvoer van blaarversnippering twee keer gedurende die blaarvalperiode het die effektiwiteit van hierdie behandeling verhoog. Hiervan kan dus afgelei word dat blaarversnippering voordelig sal wees vir die bestuur van appelskurf en in toekomstige bestuurspraktyke ingesluit moet word. Praktiese oorwegings, uniek aan Suid-Afrikaanse boorde, soos boorduitleg en die tydsberekening van blaarversnippering teenoor blaarval, moet egter in ag geneem word. Pseudothesiale digtheid (PD; die aantal pseudothesia per vrugbare letsel) en askale digtheid (AD; die aantal aski per pseudothesium) is gedurende 2012 en 2013 vir die Koue Bokkeveld (KB), 'n koue winterstreek, en warm winterstreek Elgin (EL), 'n winterstreek wat klimaatsverwarming ervaar, vergelyk. Blare, met skurf, is gedurende blaarval gepluk en oorwinter in hul gebied van oorsprong, asook in die ander klimaatstreek. Blare wat in KB versamel is en in KB oorwinter het, se PD was aansienlik hoër as dié wat in EL versamel is en in EL oorwinter het, sowel as dié wat in KB versamel is en in EL oorwinter het. Hierdie resultate stem ooreen met wat verwag is, om rede die temperatuur gedurende pseudothesiale vorming, d.w.s. die eerste vier weke na blaarval, aansienlik laer in KB as in EL was. Die PD van blare wat in EL versamel en daar oorwinter het, het egter nie betekenisvol verskil van blare wat in KB oorwinter het nie. Die AD-waardes tussen behandelings verskil nie noemenswaardig nie en word as onbeduidend beskou. Die verkrygde resultate dui aan dat daar ander faktore as temperatuur betrokke is by die beheer van PD, bv. die EL-skurfpopulasie, waar die warmer klimaat meer optimaal is vir pseudothesiale vorming, rasse wat nie in die KB-bevolking teenwoordig is nie, mag insluit. Appelknoppe en dwerg-appels is gedurende 2010, 2011 en 2012 versamel en vir die teenwoordigheid, aantal en lewensvatbaarheid van konidiospore getoets. Dwergappels is klein laatseisoen appeltjies wat reg deur die winter aan die boom bly hang; veral in die streke met warmer winters waar die bome nie die nodige koue ervaar om dormansie te voltooi nie. Met behulp van mikroskopie is ŉ hoë aantal spore op die buitenste knopweefsel en lae getalle in die binneweefsel bespeur; maar lewensvatbare spore is net in die binneweefsel van knoppe waargeneem, wat hoofsaaklik afkomstig is van boorde wat hoë vlakke van appelskurf in die vorige seisoen ervaar het. Molekulêre tegnieke, PKR-RFLP en kPKR, is gebruik vir bepaling van V. inequalis DNA hoeveelhede op die buitenste knopweefsel. Hoër getalle konidiospore is met die molekulêre analise gevind, as dié verkry met mikroskopiese ondersoek en dui op die moontlike teenwoordigheid van miselium wat nie met visuele waarneming sigbaar was nie. Meer konidiospore met 'n hoër vlak van lewensvatbaarheid is op dwerg-apples gevind en dit is moontlik 'n meer waarskynlike bron van ongeslagtelike inokulum in Suid-Afrikaanse appelboorde, as die lae getalle van lewensvatbare konidiospore op die binneweefsel van die appelknoppe.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Climate in Africa'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles